Greenhouse gas emissions from a constructed wetland in southern Sweden

This paper investigates the greenhouse gas emissions from a Swedish wetland, constructed to decrease nutrient content in sewage treatment water. To evaluate the effect of the construction in terms of greenhouse gas emissions we carried out ecosystem-atmosphere flux measurements of CO₂, CH₄ and N₂O using a closed chamber technique. To evaluate the importance of vascular plant species composition to gas emissions we distributed the measurement plots over the three dominating plant species at the field site, i.e., Typha latifolia, Phragmites australis and Juncus effusus. The fluxes of CO₂ (total respiration), CH₄ and N₂O from vegetated plots ranged from 1.39 to 77.5 (g m⁻² day⁻¹), −377 to 1387 and −13.9 to 31.5 (mg m⁻² day⁻¹) for CO₂, CH₄ and N₂O, respectively. Presence of vascular plants lead as expected to significantly higher total respiration rates compared with un-vegetated control plots. Furthermore, we found that the emission rates of N₂O and CH₄ was affected by presence of vascular plants and tended to be species-specific. We assessed the integrated greenhouse warming effect of the emissions using a Global Warming Potential over a 100-year horizon (GWP₁₀₀) and it corresponded to 431 kg CO₂ equivalents m⁻² day⁻¹. Assuming a 7-month season with conditions similar to the study period this is equal to 90 tonnes of CO₂ equivalents annually. N₂O emissions were responsible for one third of the estimated total greenhouse forcing. Furthermore, we estimated that the emission from the forested bog that was the precursor land to Magle constructed wetland amounted to 18.6 tonnes of CO₂ equivalents annually. Hence, the constructed wetland has increased annual greenhouse gas emissions by 71.4 tonnes of CO₂ equivalents for the whole area. Our findings indicate that management processes in relation to wetland construction projects must consider the primary function of the wetland in decreasing eutrophication, in relation to other positive aspects on for instance plant and animal life and recreation as well as possible negative climatic aspects of increased emissions of CH₄ and N₂O.     

Phylogenetic systematics of Colotis and associated genera (Lepidoptera: Pieridae): evolutionary and taxonomic implications

We investigated the genetic diversity and phylogenetic placement of the butterflies in the genus Colotis and eight related pierid genera using sequence information from two mitochondrial and two nuclear genes. To establish the status of species, we initially barcoded 632 specimens representative of all genera and most species and subspecies in those genera. A subset was then selected for phylogenetic analysis where additional gene regions were sequenced: 16S rRNA (523 bp), EF‐1α (1126 bp) and wg (404 bp). DNA barcode results were largely congruent with the traditional classification of species in the Colotis group, but deep splits or lack of genetic divergence in some cases supported either species‐level differentiation or synonymy. Despite using information from four genes, the deeper nodes in our phylogeny were not strongly supported, and monophyly of the ‘Colotis group’ and the genera Colotis and Eronia could not be established. To preserve the monophyly of Colotis, we revive the genus Teracolus for three outlying species previously in Colotis (i.e. Colotis eris, Colotis subfasciatus and Colotis agoye), as well as the genus Afrodryas for Eronia leda. The position of Calopieris is unresolved although it appears to be well outside the molecular variation in Colotis (s.l.). A dispersal/vicariance analysis suggested that major diversification in Colotis (s.str.) occurred in Africa with subsequent dispersal to India and Madagascar.     

DNA double-strand break repair pathways, chromosomal rearrangements and cancer

Chromosomal rearrangements, which can lead to oncogene activation and tumour suppressor loss, are a hallmark of cancer cells. Such outcomes can result from both the repair and misrepair of DNA ends, which arise from a variety of lesions including DNA double strand breaks (DSBs), collapsed replication forks and dysfunctional telomeres. Here we review the mechanisms by which non-homologous end joining (NHEJ) and homologous recombination (HR) repair pathways can both promote chromosomal rearrangements and also suppress them in response to such lesions, in accordance with their increasingly recognised tumour suppressor function. Further, we consider how chromosomal rearrangements, together with a modular approach towards understanding their etiology, may be exploited for cancer therapy.     

Rseg--an R package to optimize segmentation of SNP array data

The use of high-density SNP arrays for investigating copy number alterations in clinical tumor samples, with intra tumor heterogeneity and varying degrees of normal cell contamination, imposes several problems for commonly used segmentation algorithms. This calls for flexibility when setting thresholds for calling gains and losses. In addition, sample normalization can induce artifacts in the copy-number ratios for the non-changed genomic elements in the tumor samples. RESULTS: We present an open source R package, Rseg, which allows the user to define sample-specific thresholds to call gains and losses. It also allows the user to correct for normalization artifacts. AVAILABILITY: The R package, Rseg, is available at: http://www.cs.au.dk/~plamy/Rseg/ and runs on Linux and MS-Windows.